Commit 9c87b2ae authored by François Michel's avatar François Michel Committed by Jakub Kicinski
Browse files

netem: use a seeded PRNG for generating random losses 



Use prandom_u32_state() instead of get_random_u32() to generate
the random loss events of netem. The state of the prng is part
of the prng attribute of struct netem_sched_data.

Signed-off-by: default avatarFrançois Michel <francois.michel@uclouvain.be>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Acked-by: default avatarStephen Hemminger <stephen@networkplumber.org>
Link: https://lore.kernel.org/r/20230815092348.1449179-3-francois.michel@uclouvain.be


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 4072d97d

net/sched/sch_netem.c

+6 −5
Original line number Diff line number Diff line
@@ -206,7 +206,7 @@ static u32 get_crandom(struct crndstate *state) 
static bool loss_4state(struct netem_sched_data *q)

{

	struct clgstate *clg = &q->clg;

	u32 rnd = get_random_u32();

	u32 rnd = prandom_u32_state(&q->prng.prng_state);



	/*

	 * Makes a comparison between rnd and the transition
@@ -271,18 +271,19 @@ static bool loss_4state(struct netem_sched_data *q) 
static bool loss_gilb_ell(struct netem_sched_data *q)

{

	struct clgstate *clg = &q->clg;

	struct rnd_state *s = &q->prng.prng_state;



	switch (clg->state) {

	case GOOD_STATE:

		if (get_random_u32() < clg->a1)

		if (prandom_u32_state(s) < clg->a1)

			clg->state = BAD_STATE;

		if (get_random_u32() < clg->a4)

		if (prandom_u32_state(s) < clg->a4)

			return true;

		break;

	case BAD_STATE:

		if (get_random_u32() < clg->a2)

		if (prandom_u32_state(s) < clg->a2)

			clg->state = GOOD_STATE;

		if (get_random_u32() > clg->a3)

		if (prandom_u32_state(s) > clg->a3)

			return true;

	}